Plutonium(IV) Fluoride
Properties
| State | Solid |
| Color | Pink to tan |
| Solubility | Essentially insoluble in water; soluble in concentrated HF |
| Melting Point | 1037 °C |
About Plutonium(IV) Fluoride
Plutonium(IV) fluoride (PuF4, 319.99 g/mol) is the pink-to-tan crystalline tetrafluoride that has sat at the center of industrial plutonium chemistry since 1944, when the first gram quantities of plutonium metal at Los Alamos were produced by calcium reduction of PuF4 in a sealed bomb — that reduction is still the standard route today. Structurally PuF4 is a monoclinic UF4-type lattice, isostructural with ThF4, UF4, and NpF4, with each Pu(IV) center 8-coordinate to bridging fluorides in a square-antiprism geometry. The compound sits at the junction of the two main industrial transformations of plutonium: it is the precipitating species used to recover plutonium from PUREX raffinate streams (treat Pu(III) or Pu(IV) solutions with HF and the tetrafluoride drops out essentially quantitatively), and it is the reduction precursor that turns purified plutonium nitrate into reactor-grade plutonium metal for MOX fuel fabrication. PuF4 is also the entry point to PuF6 — fluorinate it with elemental F2 at 500 °C and you get the volatile hexafluoride used in fluoride-volatility reprocessing concepts. Standard treatment of the chemistry is in Edelstein, Fuger, Katz, and Morss's *The Chemistry of the Actinide and Transactinide Elements*.
Where you'll encounter it
If you've toured a plutonium facility at Los Alamos, Savannah River, or Sellafield, the pink PuF4 cake coming out of an HF precipitation step is the form most operators recognize on sight — it is the species that goes into the calcium-bomb crucible at the metal-fab end of the line, and it is the species that comes out of the aqueous-waste recovery line at the back end. The geometry of that bomb reduction (a sealed MgO crucible, a slug of CaH2 or Ca metal, an iodine booster) was worked out during the Manhattan Project and described in declassified Los Alamos reports; the same chemistry shows up in standard actinide references like Katz, Seaborg, and Morss. Fluoride-volatility researchers at ORNL ran kilogram-scale PuF4-to-PuF6 conversions in the 1960s as part of the Molten Salt Reactor Experiment fuel-cycle studies, and modern Generation IV concepts revisit that chemistry whenever volatile actinide separation comes back into fashion.
Common Uses
- Calcium-bomb reduction precursor for producing Pu metal at Los Alamos and Savannah River since 1944
- Fluorination feedstock for PuF6 generation in fluoride-volatility reprocessing studies at ORNL
- Insoluble precipitating form for recovering Pu from acidic aqueous waste with HF treatment
- Reference 8-coordinate Pu(IV) phase for actinide fluoride coordination and crystallography studies
- Target material in actinide separation and minor-actinide transmutation R&D
Safety Information
Pu-239 alpha emitter (specific activity 62 mCi/g); DOE 10 CFR 835 inhalation ALI ~30 nCi for soluble Pu compounds, but PuF4 is essentially water-insoluble so the dominant hazard is alpha-active dust. Generates HF on prolonged moisture exposure. SPECIAL NUCLEAR MATERIAL under DOE/NRC accountability — handled only in fluoride-compatible alpha glove boxes with HEPA exhaust and continuous air monitoring. GHS: H330 (acute inhalation toxicity Cat 2), H314 (corrosive Cat 1B), H350 (carcinogenicity Cat 1A from radioactivity).
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals.